CB Radio Mods President Lincoln FM detector fix
Some users reported a bad FM signal detection on weaker signals. This is also what I recognized at all my 3 Lincolns I owned in the past years.
The reason and the fix are simple.
The input of the FM detector stage is wired from L104 through a serial resistor of 10k (R1 in the schematic) toward the FM detector IC. But the schematic says “1k” instead.
With 10k the FM input signal is attenuated so strong, that the detection below S5 gets more and more worse. You hear more FM-noise than the FM-signal itself, meaning the S/N ratio gets worse.
The fix is easy:
MORE....... in pdf